1. Field of the Invention
The present invention relates to a technology for forming a conductive film, an insulating film, a semiconductor film and the like over a substrate by ejecting compositions to the substrate. In particular, the invention relates to a liquid droplet ejection system including a means for controlling ejection conditions of compositions, and a liquid droplet ejection method.
2. Description of the Related Art
Conventionally, a thin film transistor (TFT) used for a flat panel display (FPD) and the like is formed by depositing thin films such as a conductive film, an insulating film and a semiconductor film, and subsequently performing photolithography thereto to obtain desired shapes of the thin films and laminating them. The photolithography is a technology for obtaining a desired shape of a thin film by coating a resist over a thin film deposited over the whole surface of a substrate, exposing it to the ultraviolet light using a photomask formed by using a schematic editor such as CAD as a mask, and etching it using a mask pattern formed by a developing process (leaving a pattern by chemically treating the resist which has been exposed to light).
Meanwhile, in recent years, the use of a liquid droplet ejection system is considered for the formation of a thin film or a wiring pattern used for a semiconductor element in view of a reduction in equipment cost or simpler manufacturing steps of semiconductor elements. According to the liquid droplet ejection method, a thin film or a wiring pattern can be formed through a direct depiction by ejecting a composition, in which materials for forming the thin film or the wiring are dissolved or dispersed into a solvent, from a nozzle of a liquid droplet ejection system (a system having a cylindrical nozzle with a small hole in its distal end for ejecting liquid solution or gas) on a substrate and the like. Therefore, the aforementioned photomask is no longer required and conventional photolithography steps can be omitted, which will lead to drastically simplified steps and reduced cost.
However, when using the liquid droplet ejection method, at least a moving path of a nozzle or a substrate is required to be accurately controlled in ejecting liquid droplets instead of omitting the conventional photomask. In addition, such conditions are also desirably controlled with accuracy as a moving rate of a nozzle or a substrate, ejection quantity of compositions, ejection distance, ejection rate, atmosphere, temperature and moisture of ejection environment, and heating temperature of a substrate.